Opeth

Loosely labelled a death metal band, Opeth is really so much more,
with
their mix of mid-paced riffing, acoustic guitar interludes,
and frequent tempo and mood changes continuing to push the
boundaries of extreme music.
Opeth write long songs (often over ten minutes long), but the
diversity of the songwriting keeps things interesting.
The phrase "progressive death metal" has been used before, but it
probably fits Opeth better than any other single band.
While the earlier albums are undeniably more brutal in their
approach (and often regarded as fan favorites) it's the
later releases, starting with 2001's
Blackwater Park, where all the pieces truly fit together.
An outstanding band.